1. Field of the Invention
The present invention relates to a trapezoidal breeding cage that widens toward the top of the breeding cage, as well as to a method for breeding small animals using the same.
2. Description of the Prior Art
Recently, small animals such as mice, hamsters, rats, and guinea pigs have been bred on a large scale for use in metabolic testing of pharmaceuticals or for in vivo proliferation of human cells.
To breed such animals, trapezoidal breeding cages which widen toward the top of the breeding cage have been developed. These breeding cages can be grouped into the following types:
type (i) wherein a feeder is provided on the inside bottom of the breeding cage as shown in FIG. 13;
type (ii) wherein a relatively large feeder is wholly plunged into the breeding cage as shown in FIG. 14;
type (iii) wherein, as shown in FIG. 15, a feeder is equipped through the front wall of the breding cage in such a manner that the top opening of the feeder comes outside the breeding cage, while the lower end of the feeder comes inside the breeding cage.
The breeding cage of type (i), however, has the demerits that feed supply becomes troublesome and that inside of the breeding cage may be littered because the small animal in the breeding cage is liable to spill feed.
Small animals, specifically, those having cheek pouches, such as squirrels and hamsters, commonly have the undesirable behavior of excessively taking feed and temporarily storing it in bedding.
The breeding cage of type (ii) has the demerits that it undesirably provides a reduced resident space for small animals; and that it renders automatic feeding very difficult because, when a plurality of such breeding cages are multilayered in a rack for multiple breeding, particular breeding cages must be pulled out from the rack on feeding.
The breeding cage of type (iii) has the demerits that the feeder prevents compact stacking; and that it is not acceptable for multiple breeding because it requires a relatively large space for all the related activities such as movement, washing and drying.
In light of the above, the development of a breeding cage which can be multilayers in a rack for multiple breeding has been greatly desired, but no satisfactory means has been provided.